feat(cfold): canonicalize custom test layout

tests/mumble/custom/test_server_config_limits.py

@@ -0,0 +1,38 @@
+"""mumble — recipe-specific functional test #2 (Phase 2 P3, beyond parity).
+
+Server-limit config round-trip via the ServerConfig protocol message. The harness deploys with a
+distinctive USERS value (recipe_meta.EXTRA_ENV -> MUMBLE_CONFIG_USERS, the server's max-users cap,
+set to a non-default 42). A client that completes the handshake receives a ServerConfig message
+carrying the server's enforced limits (max_users, allow_html, message_length, ...). Asserting
+max_users == our configured value proves the recipe wires deploy-time limits into the running
+server and enforces them — a distinctive, characteristic mumble behaviour (server capacity policy),
+not health-only. Version-independent (asserts OUR configured value).
+"""
+
+from __future__ import annotations
+
+import os
+import sys
+
+sys.path.insert(0, os.path.dirname(__file__))
+sys.path.insert(0, os.path.join(os.path.dirname(__file__), ".."))
+import _mumble_proto  # noqa: E402
+import recipe_meta  # noqa: E402
+
+
+def test_configured_max_users_surfaces_in_serverconfig(live_app):
+    r = _mumble_proto.retry_handshake(attempts=12, interval=5.0)
+
+    assert r["server_sync"], f"ServerSync handshake did not complete — {r.get('error')}"
+    cfg = r["server_config"]
+    assert cfg, f"server did not send a ServerConfig message — {r!r}"
+    assert cfg.get("max_users") == recipe_meta._MAX_USERS, (
+        f"ServerConfig.max_users={cfg.get('max_users')!r} does not match the configured "
+        f"USERS={recipe_meta._MAX_USERS} — deploy-time server-limit config did not propagate"
+    )
+    # allow_html defaults true in the recipe; assert it is present/boolean to prove the field set
+    # is the real ServerConfig (not an empty/garbled decode).
+    assert cfg.get("allow_html") in (
+        0,
+        1,
+    ), f"ServerConfig.allow_html unexpected: {cfg.get('allow_html')!r}"